AS31727: the NODE4-AS network

AS31727 is an internet Autonomous System operated by NODE4-AS (the United Kingdom). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS31727?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS31727 was assigned to NODE4-AS by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS31727 currently announces 78 IPv4 block(s), totaling about 60.7 thousand addresses (60,672 in all), registered in the United Kingdom. Services from NODE4-AS are reached through these addresses.

What it means to see AS31727 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS31727. That means the other end sits on the NODE4-AS network (the United Kingdom). It can be legitimate — a cloud service, an ISP, a CDN — or an unexpected connection worth checking.

How to see every connection and network your devices reach

Tracing one connection's ASN at a time is tedious. Sentinela, by PC Monitor, maps the devices on your network, shows what is exposed to the internet and helps flag suspicious connections and devices — running on your Windows. Meet Sentinela.